Coolant pumps are important for the cooling systems of a vehicle. During operation, the coolant pumps drive coolant, such as water, circulating in the cooling systems and thus take away heat from the engine or other heat generating part, thereby ensuring that the vehicle works at a desired temperature.
According to driving modes, the coolant pumps are divided into two kinds, i.e., mechanical pumps and electric pumps. The mechanical pumps are driven by the engine of the vehicles, and thus speeds thereof are determined by the engine and cannot be adjusted. Electric pumps are controlled by independent control units, and can be adjusted according to different requirements. Accordingly, electric pumps are energy-saving and offer better temperature control of the engine, etc.
An electric pump typically includes a motor and an impeller driven by the motor. The motor includes a stator and rotor. The stator includes coils connected to the control unit electrically. The control unit controls electric current of the coils. The rotor has magnets which generate magnetic fields interacting with that of the rotor, thereby driving the rotor. The impeller is connected to and rotates with the rotor, thereby driving the coolant circulating in the cooling system to cool the engine. However, the control unit also generates a lot of heat during operation, which may affect the safety of the pump if the heat is not dissipated timely.